Possible Clues:

• The son most likely to succeed?
• As part of genteel destiny, most like to succeed
• A son of Galsworthy
• Cain, of Adam's sons
• With the most life experience
• First in line to the throne
• Meg, among the "Little Women"
• Most senior (E, not O)
• First delivered from cruel destitution
• Extremely senior personnel de-stressing amidships